An opening and closing chuck that has a pair of fingers opened and closed by being moved along a guide rail is conventionally known as disclosed in, for example, PTL 1. In this opening and closing chuck, a pair of fingers is disposed on the front surface of a casing so as to be openable and closable along a guide rail, two cylinder holes are formed in the interior of the casing so as to be parallel in the right and left direction, and pistons accommodated in the cylinder holes are individually linked to the pair of fingers with axes. The two pistons are operated by the action of air pressure to open and close the pair of fingers. Thus, an article is grasped between the pair of fingers.
In the conventional opening and closing chuck, to mutually link the pistons and fingers, cutouts like slotted holes, which communicate with the cylinder holes, are formed at positions, on the front surface of the casing, opposite to the two cylinder holes so as to be along the cylinder holes, the axes are fixed to linking pieces fixed to the fingers, a slotted hole is formed in each piston, the slotted hole being orthogonal to the axial line of the piston, and the axis is inserted into the cylinder hole through the cutout, and the top end of the axis is fitted into the slotted hole of the piston and is secured. Thus, the piston and finger are mutually linked.
However, the structure in which the pistons and fingers are mutually linked with axes through a plurality of cutouts formed in the front surface of a casing as in this opening and closing chuck is problematic in that machining of the casing is complex because the casing must be subjected to a drilling process, the plurality of cutouts lower the strength of the casing, and foreign matter such as dust enters the cylinder holes through the cutouts, causing the pistons to be likely to malfunction due to the foreign matter.